Caledoniana microgona, Galea, 2015

Galea, Horia R., 2015, Two new genera and nine new species of hydroids (Cnidaria: Hydrozoa) from off New Caledonia, European Journal of Taxonomy 135, pp. 1-19 : 6-7

Caledoniana microgona sp. nov.

urn:lsid:zoobank.org:act:798CB04B-5AB6-48B2-962D-AD9F6FE56D65

Figs 1C , 2 E–G; Table 1

Diagnosis

Colonies lightly fascicled basally, loosely branched, coplanar; nodes indistinct, internodes relatively long; hydrothecae in opposite pairs and coplanar series; long, tubular, free part slightly convex basally, then straight; gonothecae small, club-shaped.

Etymology

From the Greek ΜΙκρός, meaning "small", and γόνΟς, meaning "seed", to characterize the size of its gonothecae.

Material examined

Holotype

NEW CALEDONIA: campaign Biocal, station DW46, 22°53’ S, 167°17’ E, 570–610 m, 30 Aug. 1985; 7.3 cm high colony with one gonotheca (IK-2012-10290).

Paratypes

NEW CALEDONIA: data as for holotype; numerous fragmented stems up to 6.3 cm high, some sterile, as well as several detached gonothecae (IK-2012-10291).

Description

Colonies erect, up to 7 cm high, fan-shaped, loosely fascicled on basal portions of stems and some lower side branches. Main tube indistinctly divided into moderately long internodes, each of them bearing a distal pair of opposite, though not contiguous, hydrothecae. Side branches sparse, given off irregularly and laterally from below a hydrotheca; up to 2 nd order branching. First hydrotheca of side branch commonly unpaired, although one colony with paired hydrothecae. Hydrothecae large and tubular, immersed for about one-third of adaxial length into internode; free part of nearly constant diameter, projecting outward at wide angle; abaxial wall slightly tumid at inflexion point, then straight distally; free adaxial side slightly convex basally, then parallel to abaxial counterpart; rim thickened; aperture borne on slight terminal constriction of hydrothecal wall; in frontal view rounded on adaxial side and flattened abaxially; opercula not seen. Gonothecae given off slightly laterally from below bases of hydrothecae; small and club-shaped, with thick perisarc. Coenosarc badly preserved, not suitable for tentacle counting or cnidome studies.

Remarks

Like in C. decussata gen. et sp. nov., the free parts of the hydrothecae of this species are almost straight, thus differing from the sigmoid shape met with in C. alata gen. et sp. nov. However, in C. decussata gen. et sp. nov. the hydrothecal pairs may exhibit a decussate arrangement; their free part is comparatively shorter, while the adnate one is longer.

Figures

Fig. 1. A. Caledoniana alata gen. et sp. nov., holotype (below) and paratype (above). B. Caledoniana decussata gen. et sp. nov., colony silhouette (part of holotype). C. Caledoniana microgona gen. et sp. nov., colony silhouette (holotype). The red arrows indicate the presence of gonothecae. Scale bars: 1 cm.

Fig. 2. — A–B. Caledoniana alata gen. et sp. nov. A. Portion of fertile stem (note gonotheca above) and basal part of a side branch, showing positions of hydrothecae. B. Hydrotheca. — C–D. Caledoniana decussata gen. et sp. nov. C. Portion of stem with first and second order side branches from region of colony with coplanar hydrothecae, showing their relative position. D. Hydrotheca. — E–G. Caledoniana microgona gen. et sp. nov. E. Portion of stem. F. Hydrotheca. G. Three gonothecae. Scale bars: A, C, E, G = 3 mm; B, D, F = 1 mm.